Detergent compositions containing perfume are well known in the art. The perfume is ordinarily mixed or admixed with the liquid or granular detergent composition. Perfume makes the composition more aesthetically pleasing to the consumer, and in some cases it imparts a pleasant fragrance to surfaces. Most consumers have come to expect detergent compositions to have a pleasing odor.
Because perfumes are made of a combination of volatile compounds, perfume can be continuously emitted from simple solutions and dry mixes to which it has been added. Various techniques have been developed to hinder or delay the release of perfume from compositions so that they will remain aesthetically pleasing for a longer length of time. For example, see West German Patent 825,293, Dec. 17, 1951; East German Patent 15,693, Oct. 12, 1975; and U.S. Pat. Nos. 3,772,215, issued Nov. 13, 1973; and 3,567,119, issued Mar. 2, 1971. While such methods have been somewhat effective, there is still a need to economically formulate a composition which emits perfume from the composition and the treated surface even after product storage.
Encapsulation techniques have been used to enclose the perfume so that the fragrance is not emitted during storage and it is noticeable after actual use of the product, when the encapsulating material dissolves or breaks and the perfume is released. Storage of encapsulated perfume, though, can result in loss of the perfume stored within by capsule breakage and/or vaporization of the perfume core through the capsule wall.
Microencapsulation techniques are known for perfumes, medicines, adhesives, dyestuffs, inks, fertilizers, etc. See for example U.S. Pat. Nos. 4,446,032, Munteanu et al., issued May, 1984; 4,288,460, Ciliberto et al., issued Sept. 8, 1981; 4,268,411, Iwata et al., issued May 19, 1981 and 4,081,264, Ali, issued Mar. 28, 1978. Microencapsulation techniques and materials for forming microcapsules are disclosed in U.S. Pat. No. 2,800,458, Green, issued Jul. 23, 1957; U.S. Pat. Nos. 3,159,585, Evans et al., issued Dec. 1, 1964; 3,533,958, Yurkowitz, issued Oct. 13, 1970; 3,697,437, Fogle et al., issued Oct 10, 1972; 3,888,689, Maekawa et al., issued Jun. 10, 1975; U.S. Pat. No. 3,996,156, Matsukawa et al., issued Dec. 7, 1976; 3,965,033 Matsukawa et al., issued Jun. 22, 1976; 4,010,038, Iwasaki et al., issued Mar. 1, 1977; 4,016,098, Saeki et al., issued Apr. 5, 1977; 4,269,729, Maruyama et al., issued May 26, 1981; 4,303,548, Shimazaki et al., issued Dec. 1, 1981; 4,460,722, Igarashi et al., issued Jul. 17, 1984; 4,610,927, Igarahsi et al., issued Sept. 9, 1986; 4,961,871, Michael, issued Oct. 9, 1990; and Brit. Patent 1,483,542, published Aug 23, 1977.
Similarly, conditioning agents are known which promote the flow of solid particles. Some microencapsulation techniques have been developed which incorporate conditioning agents, such as silica particles, directly into the encapsulation material. See for example U.S. Pat. Nos. 4,268,411, issued May 19, 1981 and 4,288,460, issued Sep. 8, 1981. Although the incorporation of small particles into the perfume capsule wall is desirable to promote release by weakening the capsule wall, it Can also cause premature release of the perfume core during storage and/or handling.
It has now been found that adding silicon dioxide or aluminosilicate, which have a high adsorption efficiency, light density, water-insolubility, and/or a neutral or alkaline pH, to a wet cake containing perfume capsules, improves the fluidization and drying rate of the wet cake, and thereby enhances the flow and performance of the final perfume capsule composition. The silicon dioxide or aluminosilicate powder is believed to contribute the following advantages: (1) increases fluidization and drying rate of a wet cake, probably due to the increased interporosity and high adsorption efficiency of the powder; (2) protects perfume capsules from breakage by inhibiting contact between the perfume capsules; (3) acts as a scavenger for any perfume core which has inadvertently been released; (4) improves flow properties allowing better handling of the wet cake; and/or (5) reduces stress on the perfume capsule shell, allowing more of the capsules to be delivered without shell flaws.